From the point of the quark model, some of them can be interpreted as mesons made of quark-anti-quark pairs and
baryons constructed from three quarks. However, there is a plethora of states whose structure is puzzling, presenting properties
that can be fitted in the hadronic molecular state picture if the mass is close to the threshold of two hadrons. For example,
the first well-known hadronic molecular state is deuteron, composed of neutron-proton component. Three narrow hidden-charm
pentaquark states, named \(P_c(4312)\) , \(P_c(4440)\) , and \(P_c(4457)\) , have been reported by the LHCb Collaboration [1]}.
Their spectroscopies and decay widths can be well explained in the context of the \(\Sigma _c\bar{D}^{(*)}\)  molecular states [2]}, [3]}, [4]}, [5]}, [6]}.
